1. Field of the Invention
The present invention is directed to a method and apparatus for acoustically enhancing cooling of molten liquid. More specifically, the present invention is directed to a cooler having one or more horns for emitting acoustic energy into the cooler to thereby enhance cooling of clinker, a product used to make cement, within the cooler.
2. Description of the Related Art
Conventional techniques for producing cement are well known. Raw materials, such as limestone, clay, fly ash, and possibly other materials are mixed and ground together in a mill to produce a powder. Once mixed, the powdered raw material is fed into a kiln where it is subjected to extremely high temperatures. Subjecting the raw material powder in the kiln to extreme heat converts the powder to a molten liquid form, known as clinker.
Specifically, as part of the conversion of powdered material to a molten liquid, the ground raw materials undergo a calcining process to convert the calcium carbonate found in the limestone into another calcium compound, such as a dicalcium silicate, tricalcium silicate or tricalcium aluminate. It is these calcium compounds resulting from the calcining process which is known as clinker. Clinker, after being cooled and processed to an acceptable state, is ground with gypsum to produce cement. Cement, along with rock, sand, and water, are the key ingredients in concrete.
It is important to lock the chemical characteristics of the calcium compounds into the clinker, and it is known that if the clinker is allowed to cool slowly, some of the constituents will be lost. Therefore, it is a principal object in the production of cement to rapidly cool the molten clinker. Quickly cooling the clinker is not only advantageous for preserving the chemical characteristics of the clinker, but also for material handling purposes.
Previous attempts at cooling molten clinker typically involve passing the clinker through an elongate cooling mechanism, known as a clinker cooler. A number of fans are positioned in the cooler for propelling air into the clinker to enhance the cooling of the clinker. As the molten liquid clinker cools, it solidifies, breaks, and cracks into a large number of pieces. Typically, at the output of the clinker cooler, the chunks and pieces of clinker are subjected to a hammering process which crushes the clinker into smaller, manageable pieces of clinker.
The clinker typically is transported through the cooler on grates having apertures therein. The fans are positioned to blow air up through the apertures in the grates. Some attempts have been made to enhance clinker cooling by modifying the transporting grates so that greater quantities of air will pass up through the grates and into the molten clinker. However, modifying existing cement plants with these proposed systems is extremely expensive.
Additionally, a known problem in the cooling of clinker is what is known as a red river condition. Such a condition exists when the clinker cools more rapidly at some areas than others, resulting in a river of molten clinker flowing through or past areas of solidified clinker. The inability to solidify clinker along the river is particularly troublesome because the hot, molten clinker will quickly damage the grates upon which it is being transported in the areas of the river. Additionally, if the river proceeds all the way to the output of the clinker cooler, it is quite likely that the molten clinker will damage downstream equipment in the cement plant process, thereby resulting in production downtime.
Accordingly, a simple, inexpensive, and effective method and device for cooling clinker are needed. The present invention meets these needs and overcomes the drawbacks of the prior art.